The present invention relates to a safety syringe, and, more particularly, to a single use safety syringe.
In general, safety syringes include a barrel which has a cavity for storing a desired fluid, a needle assembly which includes a needle and which is secured to the barrel, and a plunger which is selectively inserted or removed from the cavity. Safety syringes may also include a housing which secures the needle therein.
Various mechanisms have been proposed to allow the needle to be temporarily secured in the housing prior to use of the safety syringe and to be permanently locked therein after use of the safety syringe so as to prevent further use of the safety syringe and to prevent needle pricks. For example, U.S. Pat. No. 5,980,494 discloses an exemplary safety syringe that automatically extends a needle from a housing and retracts the needle into the housing upon axial displacement of its barrel.
Although the syringe disclosed in the ""494 Patent is effective for its intended use, there is a need for a novel safety syringe which is particularly suitable for small dose injections (e.g., an insulin injection). Because such syringes are sized and shaped to allow for only a single use thereof, they typically have a relatively small size (e.g., 1 cc). Due to safety concerns, these syringes, like their larger counterparts, should prevent needle pricks and should be relatively inexpensive to manufacture.
In accordance with the present invention, a safety syringe is disclosed which includes a housing having a bore which extends from a distal end of the housing to a proximal end thereof. The safety syringe also includes a barrel being mounted for reciprocating movement within the housing such that the barrel is movable between a retracted position and an extended position. A ring is mounted to the barrel and is rotatable relative to the housing and to the barrel. The ring includes a plurality of tabs circumferentially spaced from each other. Urging means is also provided for urging the barrel toward its retracted position.
An interior wall of the housing includes a plurality of ramp means and a plurality of stop means. The ramp means is provided for rotating the ring relative to the housing and to the barrel, while the stop means is provided for stopping the rotation of the ring relative to the housing and to the barrel. Locking means is also included within the interior wall of the housing for locking the barrel in its retracted position.
In accordance with one embodiment, the interior wall of the housing includes a plurality of ramps, each of which being sized and shaped so as to allow one of the tabs to slide therealong. The interior wall of the housing also includes a plurality of stops, each of which positioned so as to be engageable by one of the tabs.
Other features and aspects of the present invention will become more fully apparent from the following detailed description of an exemplary embodiment, the appended claims and the accompanying drawings.